The invention disclosed and claimed herein generally pertains to the field of systems for applying a force to compliant material which is adjacent to the inner surface of a rigid spherical segment, so that the compliant material is controllably spread across the segment to expel air bubbles from the compliant material. More particularly, the invention pertains to such systems wherein an elastomeric spherical segment containing particulate weighting material is selectively manipulated to spread the compliant material. Even more particularly, the invention pertains to systems of the above type which are employed to fasten selected structure or material to the inner surface of a hyperhemisphere by means of a bonding adhesive, it being important to insure that no cavities or pockets are present in the adhesive after it has cured.
It has been found that if a window having the shape or configuration of a spherical segment, such as a hyperhemisphere, is employed in a submarine periscope housing system to protect optical or infrared image sensing equipment, various advantages are realized. Advantages include improved viewing capability and reduced resistance to motion through water. A periscopic housing system which employs a hyperhemispherical window has been successfully designed, fabricated and tested, and is disclosed in U.S. Pat. No. 4,150,875, issued to Jerry D. Stachiw and George M. Horn for a "Pressure Resistant Housing" on Apr. 24, 1979.
It will be readily apparent that a submarine viewing system, in order to have maximum utility, must be capable of functioning in frigid marine environments, such as an Arctic environment. Consequently, it is necessary to continually conduct substantial amounts of heat to the window of the viewing system, to prevent the formation of ice upon the external surface of the window. Ice formation must be avoided, since a coating of ice of more than minute thickness prevents both optical and infrared images from entering the window and being detected by viewing equipment contained therein.
In order to sufficiently heat a hyperhemispherical window used in a periscopic viewing system, while avoiding interference with azimuthal scanning activity of viewing equipment contained therein, an electrical heating pad, or cap heater, might be bonded to the inner surface of the hyperhemispherical window, at and around the apex thereof. In the past, attempts have been made to bond a cap heater to an inner hyperhemispherical surface by means of an adhesive material spread therebetween. However, the adhesive material generally has contained air bubbles, which could not be squeezed out of the portion of the adhesive lying between the heater and the surface, and the bubbles would cause void spaces in the adhesive after it had dried. Since heat could not flow from the cap heater to the hyperhemispherical window through such voids, the cap heater was likely to become extremely hot in the vicinity of the voids, and be severly damaged or destroyed.
In their invention, Applicants provide a system for enabling structure or a sheet of material to be adhesively bonded to the inner surface of a spherical segment in such manner that all air bubbles initially present in the adhesive are expelled therefrom. As far as is known, no tool or technique is available in the prior art which is capable of performing such task. It is anticipated that by means of their invention, a cap heater may be joined to the inner surface of a hyperhemispherical window in such manner that heat is enabled to flow from the heater to the window with substantially even or uniform heat transfer, at every point of the heater-window interface.